Apparatus for treating metals



1933- J. o. BETTERTON ET AL 1,934,479

APPARATUS FOR TREATING METALS Filed Nov. 11, 1931 INVENTORS 11 least; 0.Bella-10w B134? E. [ekedeff ATTO RN EYS Patented Nov. 7, 1933 STATESPATENT FicEi 1,934,479 7 APPARATUS FOR TREATING METALS Jesse OatmanBetterton and Yurii E. Lebedefl, Omaha, Nebn, assignors to Americansmelting & Refining Company, New York, N. $5., a corporation of NewJersey Application November 11 1931. Serial No. 574,328

9 Claims.

ization practice in lead refining. The invention provides for theremoval of the zinc as a slag and. for the processing of the slag forthe production of a valuable high zinc end product substantially freefrom lead.

The apparatus is suitable for use in removing a portion of the zinc fromthe lead bath by means of chlorine gas and removing a. further portionby means of an oxidizing agent, such as air, steam or water, andcombining the portions so removed to produce a zinc oxychloride slaghaving a controllable amount of chlorine present therein and bydeleading the oxychloride slag'to produce a zinc product which can bereadily processed for the production of commercial zinc oxide. In apreferred use of the apparatus; the above process is so carried out thatthe various by-products are utilized in a cyclic manner and the finalproducts are removed from the lead in a commercially usable form.

The invention also consists in certain new and original features ofconstruction and combina t-ions ofgparts hereinafter set forth andclaimed.

Although the novel features which are believed to becharacteristic ofthis invention will be particularly pointed out in' the claims appendedhereto, the invention itself, as to its objects and advantages, and themanner in which it may be carried out, may be better understood byreferring to the following description taken in connection .with "theaccompanying drawing forming a part thereof, in which Fig. 1 is a brokenplan view of one form of apparatus by which the present process may becarried out;

Fig. 2 is a section taken on the line 2-2 of Fig. 1 showing thedezincingchambers; and

Fig. 3 is a broken elevation of .the stirring device. 1

Like reference characters denote the several figures of the drawing.

In thefollowing description .and'in the claims, various details will beidentified by-specific names for convenience but they' are intended-to,be as generic in their application as the art will permit. Referring tothe drawing more in detailthe like parts in apparatus is shown ascomprising a kettle '10 which is adapted to contain a bath '11 of moltenlead The kettle 10 is providedwith arim 12 which rests upon a supportingmember 13, such as a floor, by which the kettle isiheld in operatingposition with respect to suitable heating devices not shown.

Resting uponthe rim of kettle 10 is a-framework 14 comprisinglongitudinal members which support a pair of chambers 15 and-16, pump1'7,

gear box 18 and driving motor 19. Pump 17 is suspended below framework14 as by struts 20 and is adapted to be immersed in bath 11 wherebymaterial from said bath is discharged through pipe 21 into chambers 15and 16. provided with a forked section 22, the two branches 23-24 ofwhich communicate through the top of chambers 15 and 16 respectively andare adapted to apply molten metal thereto.

Valve 25 maybe included in pipe 21 in a position 7 near pump 17 so thatthe flow of metal can be prevented when the pump is first placed inposition and the operation is begun. This permits the pump to be broughtup to full operating speed before any metal is discharged into chambers15 and 16. Valves 26 and 27 are located in branches 23-24 respectivelyof forked member 22 to permit regulation of the relative quantities ofmetal applied to the two chambers. Pump. 17

isdriven by motor 19 through suitable gears (not shown) which areenclosed in gear box 18. Bracket 30 may be secured to the assemblyin aposition to receive a lifting device and permit the entire assembly tobe removed from the kettle. Rim 31 may also be secured to framework 14for strengthening purposes and to provide a guard rail for the operator.

Suitable inlet pipes 32 and 33 are associated with chambers 15 and 16and are provided with Valves 34 and 35 respectively. These pipes serveto admit the reagent in controllable quantities to the reaction chamberswherein it contacts with the molten metal from pipes 23 and 24. Saidchambers are also provided with discharge pipes 36 and 37 respectivelywhich extend from the bottom of the chambers into the bath of metal andare preferably, inclined toward each other whereby mixing of theproducts of reaction from the two chambers is obtained.

A separate stirring device comprisingan impeller 40 and suitable drivingmeans is mounted onaseparate framework comprising longitudinal meansllwhich are also supported across the rim of the kettle. Said frameworkcarries driving motor 42 and gear box 43 containing a suitable V Ireduction gear by which the impeller 40 is rotated. Shafts 4.4 and 45connect the gears with'the driving qmotor and impeller respectively. Theimpeller is designed so that upon rotation thereof at a predeterminedspeed a vortex is produced Said pipe 21 is in the metal bath by means ofwhich the material resting upon the surface of said bath is drawn belowsaid surface and a thorough mixing of the various portions of the bathis obtained.

The process as applied to the dezincing of lead may be carried out bypumping lead from the Parkes desilverization process into kettle 10 at atemperature of 750 F. to 808 F. Zinc oxychloride slag from a precedingoperation is then added to the dezincing kettle together with a smallpercentage (by weight) of commercial sodium. borate, borax and/or sodiumchloride. The latter materials operate as fluxes and serve to increasethe fluidity of the slag whereby the reactions are more eiiicientlycarried out.

The bath and slag are then mixed by starting the mixing apparatusincluding impeller which is operated to produce a good vortex. Thismixing may be carried out, for example, for some 30 minutes and servesto bring the oxychloride slag into intimate contact with the bathwhereby a considerable portion of the lead held mechanically is removedandalso the lead resulting from the reduction of oxidized lead in theslag by reaction with the zinc present in the said bath and both arethus removed from the slag by entering the said metal bath. The slag maythen be removed from the surface of the bath as by skimming or tappingand treated for further deleading in a manner-to be hereinafterdescribed. 7

After the slag has been removed the dezincing apparatus is then appliedto the bath and a supply of reagent, such as chlorine gas, is connectedto one of the inlet pipes, for example, pipe-32 and the other of saidpipes 33 is connected to a source of oxidizing agent, such as compressedair.

'Pump I 1? -is then started and brought up to operating speed, afterwhich, valves 25, 26 and 27 are opened'and the molten lead supplied tothe two chambers 15 and 16; Valve 25 is preferably kept closed until thepump has been brought up to operating speed so that molten metal is notapplied through the, pipes or to the reaction chambers until suincientquantities thereof can be circulated to prevent the apparatus fromfreezing.

Thereafter, the relative supply of the metal to the two chambers iscontrolled by suitable regulation of valves 26 and 27. V a

After thecirculation has been established, the oxidizing agent, such ascompressed air, is admitted to chamber 16 by suitable regulation ofvalve 35 and serves to react with the metal flowing through the chamberand to preferentially com bine with the zinc to form zinc oxide. Whilethe reaction with the zinc is exothermic the rapidity of the reaction isnot sufficient under the above conditions to generate sufiicient heat tobalance the heat lost from the reaction chamber and from the metal bath.The process is accordingly carried on as above described until thetemperature of the bath decreases to approximately 750 F. Thereafter,chlorine gas is admitted to chamber 15 by suitable regulation of valve34 to-react with the metal passingtherethrough and form zinc chlorideand to produce sufficient heat-to maintain the temperature of thebath'substantially constant. By balancing the amount of reaction takingplace inthe two chambers, as by means of valves 26 and 27 and valves 34and 35',

it is possible to conserve the heatwhich is-producedso as to maintainthe temperature of the bath substantially constant with the use of aminimum amount of fuel.

During the above'reaction a quantity-of zinc oxide and zinc chloridewhich is obtained from the two chambers whereby a zinc oxychloride slagis produced. Borax and/ or sodium chloride may also be added at thisstage of the operation to increasethe fiuiditypf the slag and to producea fluid, uniform oxychloride slag of zinc which contains some lead.

The operation above described may be continued until the zinc content ofthe bath is reduced to comparatively low limits, as for example, 10% to15%. It is usually undesirable to carry the reaction below this pointinasmuch as the selective oxidation of zinc depends upon the relativequantities ofzinc and lead and the slag would become unduly contaminatedwith lead oxide if the reaction were further continued. Accordingly, theoperation is stopped and the oxychloride slag, which contains someleadoxide in solution, is removed as by skimming or tapping and is appliedto subsequent baths for' deleading, as above described.

After removing the oxychloride slag, circulation of the metal iscontinued through reaction chamber 15'and the'application of chlorinethereto is continued until the zinc is removed from the lead to thedesired low percentage. The zinc chloride slag, containing small amountsof lead chloride which results fromthis operation, is then skimmed fromthe kettle and used as a flux in the dezincing of further quantities oflead bullion in accordance 15 with the above process. The remaining leadis substantially free from zinc and is suitable for commercial use.

The final deleading of the zinc oxychloride slag V referred toabovemaybe accomplished by melting 129 the same over a bath of metalliczinc ora leadzinc alloy in the presence ofsufficient sodium chloride andor borax to cause the slag to remain fluid at the temperature involved.The operation is v preferably carried out by melting the slag and 25zinc orlead-zinc alloy in a suitable kettle, placing the suitable mixingdevice therein under a heat insulatingcover of conventional type andmixing at a temperature of approximately 850 F.. The borax may, ifdesired, be added to the vortex produced by the mixing machine and themixing continued until a complete reaction between the slag and the zincof the bath has been obtained. Thereafter, the bath is allowed to settleand the slag may be skimmed or tapped therefrom'substantially free fromlead. By the use of the leadzinc or rnetallic'zinc bath the lead in theoxychlorideslag will be reduced to percentages of .8% to'1.9%.

' The oxychloride slags are sensitive to slight changes intemperatureand are easily chilled with -resultant "loss" or" fluidity; For thisreason Ind .the'"teniperatures in the deleading kettle mustbe'accuratel'y controlled and the heat insulating cover-is of particularimportance. Temperatures in excess of 999 F. are objectionable due tothe formation of a zinc iron alloy, the iron being derived from thekettle. i

In accordance with the present process the necessity for such hightemperatures'is avoided 1.59

died by a suitable overhead crane.

whichmu'st be allowed to coalesce and settle out of the final slag.

The cover for the deleading kettle may be han- In suitable position thecirculating pump is in the bath of molten slag belowthe cover with themotor in the outside atmosphere above the cover.

The total additions of borax comprises approximately 2 of the Weight ofthe final deleaded oxychloride slag and the sodium chloride additionsmay amount to 5% to 10% thereof.

By the above process oxychloride slags' may be produced which vary inchlorine content from normal zinc chloride up to oxychloride slagscontaining of the zinc as ZnO and 25% as ZnClz. It is obvious thatchlorine gas will only be required in chemically equivalent amounts tothe ZnClZ existing in the final slag.

The process is made possible by reason of the fact that zinc ispreferentially oxidized by either air, steam or water at lowtemperatuers in the range of 630 F. to 750 F. Obviously, the reagentsmay be introduced into the bath in various ways such, for example,asthrough the reaction cylinder of the dezincing machine or throughoutlets located under the blades of the mixing machine, or in any othermanner, thus allowing a thorough dissemination of these reagentsthroughthe molten bath.

A dry dross is produced, but due to the low temperatures most of thelead in the dross is present as metallic particles'and all of the zincas fine powdered zinc oxide This condition permits the process to betreated with a flux, such as the zinc chloride slag above mentioned,which is capable of removing the oxidized coatings from the surfaces ofthe lead prills and allowing them to coalesce and settle out of theslag.

While certain novel features ofthe invention have been disclosed and arepointed out in the annexed claims, it will be understood that variousomissions, substitutions and changes may be made by those skilled in theart without departing from the spirit of the invention.

What is claimed is: V

1. An apparatus for treating metals con1prising a plurality of reactionchambers, means for applying molten metal to said chambers and forcontrolling the relative quantities of said metal applied to eachof saidchambers, means for independently introducing reagents into each of saidchambers and means for discharging the products of reaction togetherwith'the unreacted metal from said chambers.

2. An apparatus for treating metals comprising a plurality of closedreaction chambers adapted to contain gaseous reagents, means for passingthe metal to be reacted therewith in a substantially continuous flowthrough all of said chambers and means for controlling the relativequantities of metal applied to each of said chambers.

3. An apparatus for dezincing lead comprising a kettle adapted tocontain molten lead, a plurality of closed reaction chambers mountedabove said kettle, means for applying different gaseous reagents to saidchambers, a pump suspended in the bath of molten metal contained in saidkettle, means associated with said pump for applying a continuous streamof molten lead to each of said chambers whereby said lead reacts withthe gaseous reagents contained therein and means for dischar ing theproducts of reaction in said chambers comprising discharge pipesdepending from said chambers and extending in the bath of molten'metal asubstantial distance below the surface thereof;

' 4. An apparatus for dezincing lead comprising a kettle adapted tocontain molten lead, a plurality of closed reaction chambersmountedabove said kettle, means for applying differentgaseous reagents to saidchambers, a pump suspended in the bath of molten metal contained in saidkettle, means associated with said pump for applying a continuous streamof molten l ad to each of saidchambers whereby said lead reacts with thegaseous reagentscontained therein and means for discharging the productsof reaction in said chambers comprising discharge pipes depending fromsaid chambers and extending in the bath of molten metal a substantialdistance below the surface thereof, said pipes being inclined towardeach other whereby mixing of the products of reaction in the twochambers is facilitated.

5. In dezincing lead the combination comprising a kettle adapted tocontain a bath of molten lead, a pair of reaction chambers mounted abovesaid kettle, one of said chambers being operatively associated with asource of chlorine gas and the other of said chambers being operativelyassociated with a source of compressed air, means ,for continuouslyWithdrawing portions from said molten bath and causing one part of theportions motor and a driving train interconnecting said 7 motor and saidpump, pump being positioned to extend below the surface or" the moltenbath when the framework is resting upon said rim, pipes interconnectingsaid pump and said *chambers and adapted to receive molten metal fromsaid bath and apply the same to said chambers in a position to passsubstantially through the entire length thereof,.inlet means associatedwith each of asid chambers for applyinga gaseous reagent thereto, eachof said chambers having a downwardly extending discharge pipeincorporated therewith and adapted to extend below" the surface of thebath when said framework is positioned on the rim of said kettle. 1

7. An apparatus for treating molten metals comprising a kettle adaptedto receive a bath of said metals, a framework adapted to rest upon therim of said kettle, said framework carrying a pair of reaction chambers,a pump, a driving motor and a driving train interconnecting said motorand said pump, said pump being positioned to extend below the surface ofthe molten bath when the framework is resting upon said rim,

pipes interconnecting said pump and said chamsaid bath and apply thesame to said chambers bers and adapted to receivemolten metal from saidmetals, a framework adapted to rest upon the rim of said kettle, saidframework carrying a pair of reaction chambers, a pump, a driving motorand a driving train interconnecting said motor and said pump, said pumpbeing positioned to extend below the surface of the molten bath when theframework is resting upon said rim, pipes interconnecting said pump andsaid chambers and adapted to receive molten metal from said bath andapply the same to said chambers in a position to passsubstantiallythrough the entire length thereof, inlet means associated with each ofsaid chambers for applying-a gaseous reagent thereto, and dischargemeans associated with each of said chambers and adapted to extend belowthe surface of the bath when said framework is positioned on the rim ofsaid kettle. V i

9. In combination, a source of metal, a plurality of reaction chambers,means for supplying metal from the source thereof to each of saidchambers, means for controlling the flow of metal into each of saidchambers, means for independently introducing reagents into saidchambers and means forv returning both unreacted metal and products ofreaction to the source of metal.

JESSE OATMAN BETTERTON. YURII E. LEBEDEFF.

